1. Field of the Invention
The present invention relates to a new and useful anaerobic digestion enhancer for ruminant and pseudo ruminant digestion of organic matter roughage and thereby increases the energy available for utilization by ruminant animals. In another aspect, the invention is concerned with the promotion of microbial growth within a ruminant anaerobic digestion system through use of formate salts in combination with organic matter roughage feed rations. In yet another aspect, the invention relates to a method for promoting digestion utilization by ruminant or pseudo ruminant animals of organic matter roughage such as cellulose based materials through addition of formate salts in the ppm range of the feed ration.
2. Description of the Prior Art
Organic matter roughage such as crop residues consisting of cellulosic based waste materials such as straw, corn fodder, cotton waste, gin trash, peanut shells, natural grass land forage, mature hay products, saw dust and the like offer a significant potential feed resource for ruminant and psuedo ruminant animals. Feed lots, dairy herds, cow calf range operations, wildlife and game cultivation utilize these feed ration sources either in part with grains or in total as the only energy source. In agricultural operations, for each pound of corn, wheat, milo or other grains, there is left a cellulosic residue of about one pound. In addition to is stubble, other high production waste biomasses such as gin trash are commonly available in various parts of the world where agricultural productivity generates cotton, grain and the like. Various amounts of these residues are presently being used in animal feed and by grazing of fields. However, the utilization of the cellulose fraction of these materials is minimal because of difficulties ruminant animals have in digesting these roughage materials.
It is well-known that ruminants utilize nitrogen and starch barring materials for the production of beef and other meat products as well as in dairy products. For example, food sources commonly used in these applications can be found in the group consisting of corn, sorghum, barley, oats, wheat, rice, millet, hay, silage, potatoes, yams, root, turnips, rutabagas, corn starch, potato starch, wheat starch, starch bearing foods and the like. However, the by-products generated in the production of these various food sources are commonly disregarded with the exception of hay products and silage. Cellulosic based waste materials such as stalks, gin trash, corn cobs and low quality overgrown forage products cannot be utilized fully by the ruminant animal.
These cellulosic waste such as straw, corn fodder, cotton waste, peanut shells, saw dust and the like are highly lignified biomasses which are digested poorly, if at all, by ruminants. For example, wheat straw is only about 30-40% digested by ruminants as compared to 50-60% for conventional foliage such as alfalfa and 80-90% for grains. Some of these cellulosic waste, for example, cotton gin trash are useful only for burning, having a zero or minimum economic value in feed applications.
For years the barrier to the economic utilization of cellulosic waste has been assumed to be the lignin barriers which are responsible for low ruminant digestibility of the digestible cellulose fraction. For the most part, research and prior art approached the increased utilization of cellulosic waste by attacking or providing approaches for delignification. Once lignin is broken down by treatment such as alkaline hydrogen peroxide the result is a cellulosic residue which can be more readily digestible by the ruminant. The problem in the utilization of these chemical treatments is both a logistic as well as an environment issue. Thus while cellulosic wastes are readily available on dispensed farm locations they represent bulky materials having expensive transport costs. Transportation and treatment of such waste in centralized chemical processing facilities is uneconomical and even processing such as complex chemical predigestion of lignin is not economically desirable. Moreover, many of the chemicals utilized in breaking down the lignin complex are expensive and their residuals can upset the anaerobic digestion systems of ruminant animals.
Presently, most available information on the roughage digestion by ruminants animals has been generated through chemical pretreatment processes designed to disrupt the ligno-cellulose structure of the roughage or otherwise degrade the lignin faction that shields the digestible cellulose. While some approaches have shown promise for significantly enhancing the digestibility of low grade roughage, the application in practice has been limited by cost effectiveness. Typically, the chemicals used in the pretreatment are expensive and since these chemicals are required in considerable volume, the overall process becomes too costly for utilization. For example, a method for conversion of comminuted cellulosic agricultural waste to a formedible by ruminant animals is achieved through treatment of such waste by spraying with an aqueous solution of a mixed oxidant gas at a pH of about 11-12, to produce a water content of less than 40% and a pH of about 11.4 to 11.7 in the waste is taught by Sweeney, U.S. Pat. No. 5,032,239. This approach teaches the production of the mixed oxidant gas by a gas generator comprising an electrolytic cell.
The literature contains a rich history of methods and processes designed to improve digestibility of roughage. G. C. Fahey, Jr. (1991) and colleagues at the University of Illinois have published extensively on the use of alkaline hydrogen peroxide as a means of chemically pretreating a variety of different roughage. Others have extensively investigated ozone pretreatments of roughage; use of sodium chlorite as a chemical reagent for the pretreatment of animal feedstuffs and the like. C. R. Richardson and colleagues at Texas Tech University have published and undertaken a variety of research projects pertaining to the use of chemical pretreatments of roughage enhancement. Overall, the Departments of Animal Sciences and Chemical Engineering at Texas Tech University have endeavored to promote an interdisciplinary, cooperative research program directed at the enhancement of roughage produced in West Texas for ruminant diets. The premise at Texas Tech University has been that the typical roughage is an abundant, low density biomass which usually contains less than about 50% holocellulose. Hemicellulose and amorphous cellulose are both digestible by ruminant animals and can make up much of the holocellulose in most biomasses. The problem is that for the typical roughage, the fraction of the biomass that is digestible cellulose is usually not available to the digestive process of the animal. Thus, the in vitro coefficient of digestibility for a specific roughage may be less than 15% while the fraction of potentially digestible cellulose in the same biomass exceeds 50%. The explanation offered in such cases centers on the lignin binder found in plant tissues. The lignin content of roughage is hypothesized to effectively shield the digestible cellulose content from the digestive process. The most obvious solution for increasing digestibility, therefore has been to diminish or destroy the shielding ability of the lignin. This can and has been accomplished by any number of mechanical-chemical processes.
During the 80's several processes for the enhanced hydrolysis of cellulose found in agricultural residues where proposed wherein the goal was to increase the amount of fermentable sugars obtained from biomass which would then be used in production of fuel grade ethanol. These studies reported that mechanical grinding of biomass to a flower reduced the lignin's ability to shield cellulose. Size reduction can be accomplished by any number of comminution processes. However, the grinding of bulk biomass to such a small size (less than 60 mesh) can be expensive. Further, with respect to ruminant animals, the reduction to such small particle size also dramatically reduces the retention time of the biomass in the animals G.I. tract. Thus, what was once represented as a cheap biomass roughage may no longer be cost effective in the finely ground state and more importantly the powdered biomass will have lost the fibrous characteristics needed for retention and stimulation of the ruminant wall.
Chemically orientated pretreatments of roughage have also been utilized. Thus, when different alkali hydroxide solutions also were added to the roughage it was found that with the caustic solution increased swelling of the biomass and resulted in a partial solubilization of the lignin fraction achieved by higher pH levels. The use of ammonium hydroxide instead of a mineral alkali has also produced some successes. However, ammonia is more expensive reagent than mineral hydroxides. Ammonia also presents problems due to losses from volitization in the low pH range. In a slightly different approach, the addition of solutions of low cost mineral acids to the biomass has been shown to induce cellulose hydrolysis which releases the more soluble sugar monomers. As solutes, these simple sugars are more readily extracted from the lignin complexes. However, the amount of water required to swell the biomass structure with either the caustic or acid treatment is large, greater than 50% on a weight basis. It should be further noted that the digestive tract of ruminant animals is intolerant of the extremes of pH needed with caustic or acid treatments to produce significant changes in the digestibility of the biomass roughage. Hence, while feedlot applications of these caustic and acid pretreatment processes have been attempted, the large scale implementation in cost effectiveness have not been proven and their usage has not received wide spread commercial development.
More recently, the use of chemical oxidizers has been shown to be effective as a pretreatment process for increasing the digestibility of roughage. The more effective oxidizers have been hydrogen peroxide, ozone and hypochlorides. Except for ozone which is a gas of limited water solubility, these oxidation reagents are highly water soluble and can be applied as aqueous solutions. Published research results, Tock (1982), indicate, however that these chemical oxidizers preferentially react with a lignin faction. One problem with this approach is that these reagents are expensive and when used, even in moderate quantities, can make the low cost roughage too expensive for use in formulating cattle feeds. Moreover, the processing equipment needed to contact significant quantities of these oxidizers with the roughage is somewhat more complicated due to their increased reactivity and by the requirement that these chemicals must be safely stored or generated on site. Thus, while the results look promising, there is no complete understanding of the cost involved nor of the animals digestion process for roughage pretreatment with such chemical oxidizers.
These respective approaches and techniques along with their various difficulties promoted the need for a simple, economical, environmentally safe and ruminant safe enhancer for ruminant or pseudo ruminant digestion of organic matter roughage. An approach was required which did not destroy a significant portion of the biomass lignin nor to even reduce its shielding effects but to some how prepare the roughage biomass for biological degradation in the rumen.
It can be seen that for improved economy, environmental safety and safety to the ruminant animal, a treatment which increases the digestibility coefficients achievable with low level chemical enhancer pretreatment of cellulose based roughage can, after treatment, be utilized as a larger fraction of the total feed ration of ruminant or semi ruminant animals. Not only is roughage pretreatment available for feedlot industry purposes but also for ruminant or pseudo ruminant animals where these animals are consuming low quality range plants. The feedlot operator, the range cattle/sheep operator, the dairyman will be able to experience increased flexibility in the variety of roughage available for diet formulations and still experience increases in overall total cost effectiveness and feed efficiencies while maintaining high animal energy levels either for maintenance, production of weight gain or milk. It would be most beneficial to the feedlot operator, rancher, wildlife manager, dairyman and the like if such an enhancer can be made available either as a premix for mixing with roughage, a control release salt or mineral supplement block sources for ranch animals, wherein the enhancer is only required at a level of about 100 ppm of total feed ration or greater. The enhancer can be stored locally, is environmentally friendly and promotes anaerobic digestion found in the ruminant. Such an enhancer based on formate salts has been found to satisfy all the requirements of economics and safety including the safety to the ruminant system while promoting a substantial increased utilization of the food value of cellulosic based roughages by the ruminant animal.